I've owned both the 17LS and the 16LS2. Never had the chance to listen to either the 17LS2 or the ET3SE. From what I've heard (had my Premier 140 power amp upgraded by c-j with their Teflon caps) and read, the Teflon caps bring greater clarity and dynamics to the table. Also, better frequency extension at both ends.
I agree with Marco1 that the 16LS2 was the sweet spot in c-j's older line of preamps and while you might not be able to get one for $3k, for a few hundred more, you could. From what I remember of how the 17LS sounded, the 17LS2 should be outstanding. It also has the advantage of only using 4 tubes versus the 6 needed for the 16LS2.
The 16LS2 is going to sound a little sweeter than the 17LS2, so that may be a factor in your decision. Bottom line, I don't think you'll be disappointed with any of these models.
I agree with Marco1 that the 16LS2 was the sweet spot in c-j's older line of preamps and while you might not be able to get one for $3k, for a few hundred more, you could. From what I remember of how the 17LS sounded, the 17LS2 should be outstanding. It also has the advantage of only using 4 tubes versus the 6 needed for the 16LS2.
The 16LS2 is going to sound a little sweeter than the 17LS2, so that may be a factor in your decision. Bottom line, I don't think you'll be disappointed with any of these models.